In an existing communication system, when there is data to be transmitted, data frames are transmitted from a Service Radio Network Controller (SRNC) to a Node B through downlink transmission and are transmitted from the Node B to the SRNC through uplink transmission in each transmission interval at a Iub interface (which is an interface between a Node B and an SRNC) and a Iur interface (which is an interface between an SRNC and a Radio Network Controller (RNC)). An Enhanced Dedicated Transport Channel (E-DCH) data frame is of a data frame type, which is used for uplink and involved in through an upper-layer signaling indication. The E-DCH data frames are defined as two structures: type 1 and type 2. If a Medium Access Control-enhanced sublayer Protocol Data Unit (MAC-es PDU) is involved, the structure of the type 1 is used; and if a Medium Access Control-improved sublayer Protocol Data Unit (MAC-is PDU) is involved, the structure of the type 2 is used.
FIG. 1 is a schematic diagram of E-DCH uplink data frame formats according to related technologies. As shown in FIG. 1, the E-DCH data frame of the type 1 (as shown in FIG. 1 (a)) and type 2 (as shown in FIG. 1(b)) have two components: a head and a payload, both of which include the following domains, but include different types of data units:
1. Head Cyclical Redundancy Check (CRC) Code Domain
the “CRC code” domain is that the check code applied to a head redundancy frame part (i.e., from 0 of the first byte to 0 of the last byte of the head, including 0 in the last byte but not including the last 4 bits of the head CRC, i.e., the 7th to 4th bits of the second byte) corresponds to the check code of a generator formula; the “head CRC code” domain length of the E-DCH uplink data frame is 7 or 11 bits; the 7 bits include the 7th to 1st bits of the first byte in the E-DCH data frame head; and the 11 bits include the 7th to 1st bits of the first byte as well as the 7th to 4th bits of the second byte;
2. Frame Type Indication
the “frame type indication” domain is used for indicating whether the frame is a data frame or a control frame; the length of the “frame type” domain is one bit which locates at the bit 0 of the first byte of the E-DCH data frame head; the E-DCH data frame is an uplink data frame, so the “frame type indication” domain indicates 0;
3. Frame Sequence Number (FSN)
the “FSN” domain represents the FSN of an E-DCH data frame; E-DCH data frames transmitted each time will generate their own FSNs; and a 4-bit FSN is calculated according to the following formula:FSN=(FSN+1)modulo 16
the FSN value is in the range of 0-15; the length of the “FSN” domain is 4 bits which locates from bit 3 to bit 0 of the second byte of the E-DCH data frame head;
4. The Number of Subframes
“the number of subframes” domain indicates how many subframes are in the frame; it is noted that a subframe includes a head part and a payload part; the value of the “the number of subframes” domain is in the range from 1 to 16; the binary codes of value 1 and value 16 are “0000” and “1111” respectively; and the length of “the number of subframes” domain is 4 bits which locates from bit 3 to bit 0 of the third byte of the E-DCH data frame head;
5. Connection Frame Number (CFN)
for the E-DCH, the “connection frame number” domain indicates a radio frame where data are decoded correctly in an HARQ process; for the E-DCH, the CFN (and sub-frame number) can be used for a dynamical delay measurement besides for rearrangement, with a value range from 0 to 255; the length of the “CFN” domain is 8 bits which locates from the bit 7 to bit 0 of the fourth byte of the E-DCH data frame head;
6. The Number of HARQ Retransmissions
“the number of HARQ retransmissions” domain indicates the number of HARQ retransmissions for successfully decoding payloads, or the number of HARQ retransmissions when a HARQ decoding failure is detected in the case where an HARQ decoding failure occurs; and when the value of the domain is 13, it indicates that the retransmitted actual data are not suitable for serving as an input of an Outer Loop Power Control (OLPC); when the value of the domain is 15, it indicates that the Node B cannot calculate the number of HARQ retransmissions; and the value of the domain is in the range from 0 to 15; the length of the “the number of HARQ retransmissions” domain is 4 bits which locates from the bit 3 to bit 0 of the fifth byte of the E-DCH data frame head; “the number of HARQ retransmissions” domain of the first subframe number locates from the bit 6 to bit 3 of the fifth byte of the E-DCH data frame head; “the number of HARQ retransmissions” domain of the second subframe number locates from the bit 6 to bit 3 in the first byte after the first MAC-e head of the E-DCH data frame head; the locations of “the number of HARQ retransmissions” domains of other subframe numbers in the E-DCH data frame head can be deduced by analogy, till the subframe include the number of HARQ retransmissions of all the MAC-es PDUs.
7. Subframe Number
the “subframe number” domain indicates the subframe number where the received payload locates; the subframe number (and control frame number) can be used for a dynamical delay measurement besides for rearrangment; the “subframe number” domain is in the value range from 0 to 4 and the length is 3 bits; the first subframe number locates from the bit 2 to bit 0 of the fifth byte of the E-DCH data frame head; the second subframe number locates from the bit 2 to bit 0 in the first byte after the first MAC-e or MAC-i head of the E-DCH data frame head; and other subframe numbers locate from the bit 2 to bit 0 in the first byte after the previous MAC-e or MAC-i head of the E-DCH data frame head till all the subframe numbers are included;
8. Residual Extension
the “residual extension” domain indicates the locations of new Information Elements (IEs) to be added in a backward compatibility manner; the length of the domain is 0-32 bytes;
9. Payload CRC
the “payload CRC” domain is a CRC check of a payload; the CRC is applied to the residual part of the payload, i.e., from the bit 7 of the first byte of the payload to the bit 0 of the payload before the payload CRC; the length of the domain is 16 bits.
If an E-DCH payload is decoded successfully, the E-DCH data frame is written in abovementioned format and transmitted to an SRNC by a Node B.
If the E-DCH payload fails to be decoded and meets any one of the following conditions, the service Node B will transmit an HARQ failure indication to the SRNC (non-service Node B will not transmit an HARQ failure indication):
condition 1: for an HARQ process, an MAC-e or MAC-i PDU cannot be successfully decoded, and a Retransmission Sequence Number (RSN) indicates a new MAC-e or MAC-i PDU transmission used for the same HARQ process, and the number of HARQ retransmissions having happened is equal to or higher than the minimum value of the maximal HARQ retransmission value of the MAC-d flow configured by a terminal;
condition 2: for an HARQ process, an MAC-e or MAC-i fails to be decoded all the time and the maximal retransmission of an MAC-dedicated (MAC-d) flow in the maximal retransmission of the highest HARQ which is available to the terminal connection occurs, or under the condition that an out-of-band signalling (such as an RSN) related to the HARQ on an E-DCH Dedicated Physical Control Channel (E-DPCCH) cannot be decoded, the maximal retransmission of an MAC-d flow in the maximal retransmission of the highest HARQ which is available to the terminal connection should occur;
condition 3: when the MAC-e or MAC-i is reset on a terminal, an MAC-e or MAC-i in an HARQ process fails to be decoded all the time; a Node B acquires the resetting time point of the MAC-e or MAC-i in the terminal through an upper layer.
An HARQ failure indication is transmitted only in one transmission bearer. The Node B selects any transmission bearer associated with the terminal related to an HARQ failure indication.
An HARQ failure, which is indicated in a user data frame, is called an HARQ failure indication data frame, the concrete setting is as follows; FIG. 2 is a schematic diagram of an HARQ failure indication data frame format according to related technologies. As shown in FIG. 2:
1. when a failure is detected, the IEs values of a connection frame number and a subframe number will reflect a time point;
2. type 1 is shown in FIG. 2a: the number of MAC-es PDUs will be set as 0, wherein there is correspondingly no IEs of DDI and N in the head; and for the alignment of 8 bytes, the last 4 padding bits of the IEs of the MAC-es PDU are used and there is no MAC-es PDU in the payload part of the data frame related to the HARQ failure;
3. type 2 is shown in FIG. 2b: the number of the MAC-is PDUs will be set as 0, wherein there is correspondingly no IEs of the MAC-is protocol data descriptor in the head; and there is no MAC-is PDU in the payload part of the data frame related to the HARQ failure;
4. the IE of the number of HARQ retransmissions will be set as the number of HARQ retransmissions which have happened when the failure is detected, wherein the encoding method is the same as the method of correctly decoding the payload described above.
The SRNC decodes a received, correctly decoded E-DCH data frame head to obtain the number of HARQ retransmissions, and takes it as an input of the OLPC, or decodes an E-DCH data frame head of the HARQ failure indication to obtain the number of HARQ retransmissions and takes it as an input of the OLPC. If the output Signal Interference Ratio (SIR) of the OLPC is modified, the SRNC includes a new SIR target in an OLPC frame and transmits it to the Node B. An inner loop power control function at the Node B will control the power transmission of the terminal through a new SIR target value so as to minimize interference and maintain connection quality.
Along with technology development, it is desired to introduce a dual-carrier technology (which makes a terminal able to transmit data over two carriers so as to double an uplink data rate) into the existing system; furthermore, each carrier has an independent transmission bearer at a Iub interface/Iur interface. If the existing HARQ failure indication is used, there are the following problems:
since the Node B receives an MAC-es PDU or MAC-is PDU on two carriers from a terminal at an air interface, it is possible that the data on the two carriers fails to be decoded at the same time or the data on one carrier is decoded successfully while the other fails; however, the HARQ failure indication in the prior art aims at the decoding failure of the MAC-es PDU or MAC-is PDU on one carrier; the HARQ failure indication has no carrier characteristics and is transmitted to the Node B from any one of transmission bearers connected with the terminal; if both of the MAC-e PDU and the MAC-i PDU received by the Node B from two carriers fail to be decoded, or one from one carrier thereof fails to be decoded, this failure is transmitted to the Node B by using an existing HARQ failure indication data frame over any one of the transmission bearers connected with the terminal; both the HARQ failure indication data frame and the transmission bearer cannot tell which carrier the number of HARQ retransmissions belongs to, so the SRNC cannot know the number of retransmissions of the data flow on each carrier; at the same time, the OLPC is calculated based on the HARQ retransmitted data of the E-DCH frame protocol data frame head or the HARQ retransmitted data of the HARQ failure indication data frame head, so the OLPC also cannot realize the function thereof.